Determining an association between dmrs and ptrs

ABSTRACT

Apparatuses, methods, and systems are disclosed for determining an association between DMRS and PTRS. One apparatus includes a processor that: determines a scheduled physical resource block position and bandwidth; and determines, based on the scheduled physical resource block position and bandwidth, an associated demodulation reference signal port index within the physical resource block for a phase tracking reference signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 16/638,373filed on Feb. 11, 2020, which is hereby incorporated by reference in itsentirety.

FIELD

The subject matter disclosed herein relates generally to wirelesscommunications and more particularly relates to determining anassociation between a demodulation reference signal and a phase trackingreference signal.

BACKGROUND

The following abbreviations are herewith defined, at least some of whichare referred to within the following description: Third GenerationPartnership Project (“3GPP”), Positive-Acknowledgment (“ACK”), BinaryPhase Shift Keying (“BPSK”), Clear Channel Assessment (“CCA”), CyclicPrefix (“CP”), Cyclical Redundancy Check (“CRC”), Channel StateInformation (“CSI”), Code Division Multiplexing (“CDM”), Common SearchSpace (“CSS”), Channel Quality Indicator (“CQI”), Codeword (“CW”),Discrete Fourier Transform (“DFT”), Discrete Fourier Transform Spread(“DFTS”), Downlink Control Information (“DCI”), Downlink (“DL”),Demodulation Reference Signal (“DMRS”), Downlink Pilot Time Slot(“DwPTS”), Enhanced Clear Channel Assessment (“eCCA”), Enhanced MobileBroadband (“eMBB”), Evolved Node B (“eNB”), European TelecommunicationsStandards Institute (“ETSI”), Frame Based Equipment (“FBE”), FrequencyDivision Duplex (“FDD”), Frequency Division Multiple Access (“FDMA”),Frequency Division Multiplexing (“FDM”), Frequency Division OrthogonalCover Code (“FD-OCC”), Guard Period (“GP”), Hybrid Automatic RepeatRequest (“HARQ”), Internet-of-Things (“IoT”), Licensed Assisted Access(“LAA”), Load Based Equipment (“LBE”), Listen-Before-Talk (“LBT”), LongTerm Evolution (“LTE”), Multiple Access (“MA”), Modulation Coding Scheme(“MCS”), Machine Type Communication (“MTC”), Multiple Input MultipleOutput (“MIMO”), Multi User Shared Access (“MUSA”), Multiple User(“MU”), Narrowband (“NB”), Negative-Acknowledgment (“NACK”) or (“NAK”),New Data Indicator (“NDP”), Next Generation Node B (“gNB”),Non-Orthogonal Multiple Access (“NOMA”), Orthogonal Frequency DivisionMultiplexing (“OFDM”), Primary Cell (“PCell”), Physical BroadcastChannel (“PBCH”), Physical Downlink Control Channel (“PDCCH”), PhysicalDownlink Shared Channel (“PDSCH”), Pattern Division Multiple Access(“PDMA”), Physical Hybrid ARQ Indicator Channel (“PHICH”), Pre-codingMatrix Indicator (“PMI”), Physical Random Access Channel (“PRACH”),Physical Resource Block (“PRB”), Phase Tracking Reference Signal(“PTRS”), Physical Uplink Control Channel (“PUCCH”), Physical UplinkShared Channel (“PUSCH”), Quality of Service (“QoS”), Quadrature PhaseShift Keying (“QPSK”), Rank Indicator (“RI”), Radio Resource Control(“RRC”), Random Access Procedure (“RACH”), Random Access Response(“RAR”), Resource Element (“RE”), Radio Network Temporary Identifier(“RNTI”), Reference Signal (“RS”), Remaining Minimum System Information(“RMSI”), Resource Spread Multiple Access (“RSMA”), Round Trip Time(“RTT”), Receive (“RX”), Sparse Code Multiple Access (“SCMA”),Scheduling Request (“SR”), Single Carrier Frequency Division MultipleAccess (“SC-FDMA”), Secondary Cell (“SCell”), Shared Channel (“SCH”),Signal-to-Interference-Plus-Noise Ratio (“SINR”), System InformationBlock (“SIB”), Synchronization Signal (“SS”), Single User (“SU”),Transport Block (“TB”), Transport Block Size (“TB S”), Time-DivisionDuplex (“TDD”), Time Division Multiplex (“TDM”), Time DivisionOrthogonal Cover Code (“TD-OCC”), Transmission Time Interval (“TTI”),Total Radiated Power (“TRP”), Transmit (“TX”), Uplink ControlInformation (“UCI”), User Entity/Equipment (Mobile Terminal) (“UE”),Uplink (“UL”), Universal Mobile Telecommunications System (“UMTS”),Uplink Pilot Time Slot (“UpPTS”), Ultra-reliability and Low-latencyCommunications (“URLLC”), and Worldwide Interoperability for MicrowaveAccess (“WiMAX”). As used herein, “HARQ-ACK” may represent collectivelythe Positive Acknowledge (“ACK”) and the Negative Acknowledge (“NACK”).ACK means that a TB is correctly received while NACK (or NAK) means a TBis erroneously received.

In certain wireless communications networks, PTRS and DMRS ports may beassociated. In such networks, the way the PTRS and DMRS ports areassociated may be unknown.

BRIEF SUMMARY

Apparatuses for determining a SINR are disclosed. Methods and systemsalso perform the functions of the apparatus. In one embodiment, theapparatus includes a receiver that receives information from a remoteunit on an uplink channel. In certain embodiments, the apparatusincludes a processor that determines a signal-to-interference-plus-noiseratio for a scheduling layer for the remote unit based on the receiverreceiving the information from the remote unit on the uplink channel.

In one embodiment, the information from the remote unit on the uplinkchannel includes a report from the remote unit. In certain embodiments,the report includes channel quality indication reporting correspondingto two code words. In various embodiments, in response to a channelquality indication of a second codeword of the two code words indicatinga better channel quality than a channel quality indication of a firstcodeword of the two codewords, the processor swaps a modulation andcoding scheme, a transport block size, or a combination thereof of thefirst and second codewords in downlink control information.

In some embodiments, in response to a channel quality indication of asecond codeword of the two code words indicating a better channelquality than a channel quality indication of a first codeword of the twocodewords, the processor performs a precoder column permutation forlayer 0 and a smallest layer of the second codeword. In one embodiment,the report includes signal-to-interference-plus-noise ratio reporting orchannel quality indication reporting for each layer of multiple layers.In a further embodiment, in response to asignal-to-interference-plus-noise ratio report of layer 0 not being abest signal-to-interference-plus-noise ratio report or a channel qualityindication report of layer 0 not being a best channel quality indicationreport, the processor performs a precoder column permutation for layer 0and a layer having the best signal-to-interference-plus-noise ratioreport or the best channel quality indication report.

In certain embodiments, in response to the layer having the bestsignal-to-interference-plus-noise ratio report or the best channelquality indication report belonging to a second codeword, the processorswaps a modulation and coding scheme, a transport block size, or acombination thereof of the first codeword and a second codewords indownlink control information. In various embodiments, thesignal-to-interference-plus-noise ratio is based on a measurement of theuplink channel. In one embodiment, in response to asignal-to-interference-plus-noise ratio of layer 0 not being a largestsignal-to-interference-plus-noise ratio based on the measurement, theprocessor performs a precoder column permutation for layer 0 and a layerhaving the largest signal-to-interference-plus-noise ratio. In someembodiments, in response a largest signal-to-interference-plus-noiseratio based on the measurement belonging to a second codeword, theprocessor performs a precoder column permutation between the firstcodeword and a second codeword.

In various embodiments, in response a largestsignal-to-interference-plus-noise ratio based on the measurementbelonging to a second codeword, the processor swaps a modulation andcoding scheme, a transport block size, or a combination thereof of thefirst codeword and a second codewords in downlink control information.In certain embodiments, in response a largestsignal-to-interference-plus-noise ratio based on the measurementbelonging to a second codeword, the processor recalculates a modulationand coding scheme, a transport block size, or a combination thereof ofthe first codeword and indicates the modulation and coding scheme, thetransport block size, or a combination thereof in downlink controlinformation.

A method for determining a SINR, in one embodiment, includes receivinginformation from a remote unit on an uplink channel. In certainembodiments, the method includes determining asignal-to-interference-plus-noise ratio for a scheduling layer for theremote unit based on receiving the information from the remote unit onthe uplink channel.

In one embodiment, an apparatus for measuring SINR includes a processorthat: determines a configuration of downlink reference signal ports; andmeasures a signal-to-interference-plus-noise ratio of each layer ofmultiple layers based on the configuration.

In one embodiment, the processor performs codeword to layer mappingbased on a number of layers of the multiple layers. In certainembodiments, the apparatus includes a transmitter that transmits areport including a largest signal-to-interference-plus-noise ratio layerbased on measuring the signal-to-interference-plus-noise ratio of eachlayer.

In various embodiments, the processor determines a precoding matrixbased on measuring the signal-to-interference-plus-noise ratio of eachlayer. In some embodiments, each column of the precoding matrix includesa precoding vector, and each precoding vector is determined based on acorresponding layer of the multiple layers. In one embodiment, inresponse to a largest signal-to-interference-plus-noise ratiocorresponding to a layer that is not layer 0, the processor exchanges inthe precoding matrix the precoding vector for layer 0 with the precodingvector for the layer having the largestsignal-to-interference-plus-noise ratio to produce a permutatedprecoding matrix. In a further embodiment, the processor determines achannel quality indication for each codeword of multiple codewords basedon the permutated precoding matrix. In certain embodiments, theapparatus includes a transmitter that transmits a report including thechannel quality indication for each codeword. In various embodiments, abase unit determines the permutated precoding matrix based on a layerhaving a largest signal-to-interference-plus-noise ratio and theprecoding matrix. In one embodiment, the apparatus includes atransmitter that transmits a report including the precoding matrix.

A method for measuring SINR, in one embodiment, includes determining aconfiguration of downlink reference signal ports. In variousembodiments, the method includes measuring asignal-to-interference-plus-noise ratio of each layer of multiple layersbased on the configuration.

In one embodiment, an apparatus for determining an association betweenDMRS and PTRS includes a processor that: determines a scheduled physicalresource block position and bandwidth; and determines, based on thescheduled physical resource block position and bandwidth, an associateddemodulation reference signal port index within the physical resourceblock for a phase tracking reference signal.

In one embodiment, the processor associates the phase tracking referencesignal to a demodulation reference signal port based on the physicalresource block bearing phase tracking reference signal with a smallestphysical resource block index. In certain embodiments, the processorassociates the phase tracking reference signal to the smallestdemodulation reference signal port index for the physical resource blockbearing phase tracking reference signal with smallest physical resourceblock index.

In various embodiments, the processor associates, based on a scheduledphysical resource block position in a carrier or bandwidth part, thephase tracking reference signal to a demodulation reference signal portindex for the physical resource block bearing phase tracking referencesignal with smallest physical resource block index. In some embodiments,the processor associates the phase tracking reference signal to theindicated demodulation reference signal port in downlink controlinformation, radio resource control, or a combination thereof for thephysical resource block bearing phase tracking reference signal withsmallest physical resource block index. In one embodiment, the processordetermines a demodulation reference signal port index difference foradjacent phase tracking reference signals bearing physical resourceblocks. In a further embodiment, the determined demodulation referencesignal port index difference is based on a demodulation reference signalport difference between two codewords. In certain embodiments, thedetermined demodulation reference signal port index difference is basedon a default value. In various embodiments, the determined demodulationreference signal port index difference is based on signaling by downlinkcontrol information, radio resource control, or a combination thereof.In one embodiment, the signaling is part of an uplink grant or adownlink assignment.

In some embodiments, the processor determines a phase tracking referencesignal resource element position within a physical resource block basedon the demodulation reference signal port index. In certain embodiments,the processor determines a phase tracking reference signal precodingvector to be the same as a precoding vector of the associateddemodulation reference signal port. In various embodiments, theprocessor determines a phase tracking reference signal resource elementposition within a physical resource block based on a smallestdemodulation reference signal port index. In some embodiments, theprocessor determines a phase tracking reference signal resource elementposition within a physical resource block based on radio resourcecontrol signaling.

A method for determining an association between DMRS and PTRS, in oneembodiment, includes determining a scheduled physical resource blockposition and bandwidth. In certain embodiments, the method includesdetermining, based on the scheduled physical resource block position andbandwidth, an associated demodulation reference signal port index withinthe physical resource block for a phase tracking reference signal.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the embodiments briefly described abovewill be rendered by reference to specific embodiments that areillustrated in the appended drawings. Understanding that these drawingsdepict only some embodiments and are not therefore to be considered tobe limiting of scope, the embodiments will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings, in which:

FIG. 1 is a schematic block diagram illustrating one embodiment of awireless communication system for determining an association betweenDMRS and PTRS;

FIG. 2 is a schematic block diagram illustrating one embodiment of anapparatus that may be used for determining an association between DMRSand PTRS;

FIG. 3 is a schematic block diagram illustrating one embodiment of anapparatus that may be used for determining an association between DMRSand PTRS;

FIG. 4 is a schematic block diagram illustrating one embodiment of aDMRS pattern;

FIG. 5 is a schematic block diagram illustrating one embodiment of aPTRS pattern;

FIG. 6 is a schematic flow chart diagram illustrating one embodiment ofa method for swapping MCS and/or TBS between two CWs;

FIG. 7 is a schematic block diagram illustrating one embodiment of MCSand TBS in two CWs before swapping the MCS and TBS;

FIG. 8 is a schematic block diagram illustrating one embodiment of MCSand TBS in two CWs after swapping the MCS and TBS;

FIG. 9 is a schematic flow chart diagram illustrating one embodiment ofa method for precoder permutation;

FIG. 10 is a schematic block diagram illustrating one embodiment of DMRSfor multiple users;

FIG. 11 is a schematic block diagram illustrating one embodiment of PTRSfor multiple users;

FIG. 12 is a schematic flow chart diagram illustrating one embodiment ofa method for determining a SINR; and

FIG. 13 is a schematic flow chart diagram illustrating one embodiment ofa method for measuring SINR; and

FIG. 14 is a schematic flow chart diagram illustrating one embodiment ofa method for determining an association between DMRS and PTRS.

DETAILED DESCRIPTION

As will be appreciated by one skilled in the art, aspects of theembodiments may be embodied as a system, apparatus, method, or programproduct. Accordingly, embodiments may take the form of an entirelyhardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore,embodiments may take the form of a program product embodied in one ormore computer readable storage devices storing machine readable code,computer readable code, and/or program code, referred hereafter as code.The storage devices may be tangible, non-transitory, and/ornon-transmission. The storage devices may not embody signals. In acertain embodiment, the storage devices only employ signals foraccessing code.

Certain of the functional units described in this specification may belabeled as modules, in order to more particularly emphasize theirimplementation independence. For example, a module may be implemented asa hardware circuit comprising custom very-large-scale integration(“VLSI”) circuits or gate arrays, off-the-shelf semiconductors such aslogic chips, transistors, or other discrete components. A module mayalso be implemented in programmable hardware devices such as fieldprogrammable gate arrays, programmable array logic, programmable logicdevices or the like.

Modules may also be implemented in code and/or software for execution byvarious types of processors. An identified module of code may, forinstance, include one or more physical or logical blocks of executablecode which may, for instance, be organized as an object, procedure, orfunction. Nevertheless, the executables of an identified module need notbe physically located together, but may include disparate instructionsstored in different locations which, when joined logically together,include the module and achieve the stated purpose for the module.

Indeed, a module of code may be a single instruction, or manyinstructions, and may even be distributed over several different codesegments, among different programs, and across several memory devices.Similarly, operational data may be identified and illustrated hereinwithin modules, and may be embodied in any suitable form and organizedwithin any suitable type of data structure. The operational data may becollected as a single data set, or may be distributed over differentlocations including over different computer readable storage devices.Where a module or portions of a module are implemented in software, thesoftware portions are stored on one or more computer readable storagedevices.

Any combination of one or more computer readable medium may be utilized.The computer readable medium may be a computer readable storage medium.The computer readable storage medium may be a storage device storing thecode. The storage device may be, for example, but not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, holographic,micromechanical, or semiconductor system, apparatus, or device, or anysuitable combination of the foregoing.

More specific examples (a non-exhaustive list) of the storage devicewould include the following: an electrical connection having one or morewires, a portable computer diskette, a hard disk, a random access memory(“RAM”), a read-only memory (“ROM”), an erasable programmable read-onlymemory (“EPROM” or Flash memory), a portable compact disc read-onlymemory (“CD-ROM”), an optical storage device, a magnetic storage device,or any suitable combination of the foregoing. In the context of thisdocument, a computer readable storage medium may be any tangible mediumthat can contain, or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

Code for carrying out operations for embodiments may be any number oflines and may be written in any combination of one or more programminglanguages including an object oriented programming language such asPython, Ruby, Java, Smalltalk, C++, or the like, and conventionalprocedural programming languages, such as the “C” programming language,or the like, and/or machine languages such as assembly languages. Thecode may execute entirely on the user's computer, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (“LAN”) or a wide area network (“WAN”), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment. Thus, appearances of the phrases“in one embodiment,” “in an embodiment,” and similar language throughoutthis specification may, but do not necessarily, all refer to the sameembodiment, but mean “one or more but not all embodiments” unlessexpressly specified otherwise. The terms “including,” “comprising,”“having,” and variations thereof mean “including but not limited to,”unless expressly specified otherwise. An enumerated listing of itemsdoes not imply that any or all of the items are mutually exclusive,unless expressly specified otherwise. The terms “a,” “an,” and “the”also refer to “one or more” unless expressly specified otherwise.

Furthermore, the described features, structures, or characteristics ofthe embodiments may be combined in any suitable manner. In the followingdescription, numerous specific details are provided, such as examples ofprogramming, software modules, user selections, network transactions,database queries, database structures, hardware modules, hardwarecircuits, hardware chips, etc., to provide a thorough understanding ofembodiments. One skilled in the relevant art will recognize, however,that embodiments may be practiced without one or more of the specificdetails, or with other methods, components, materials, and so forth. Inother instances, well-known structures, materials, or operations are notshown or described in detail to avoid obscuring aspects of anembodiment.

Aspects of the embodiments are described below with reference toschematic flowchart diagrams and/or schematic block diagrams of methods,apparatuses, systems, and program products according to embodiments. Itwill be understood that each block of the schematic flowchart diagramsand/or schematic block diagrams, and combinations of blocks in theschematic flowchart diagrams and/or schematic block diagrams, can beimplemented by code. The code may be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the schematic flowchartdiagrams and/or schematic block diagrams block or blocks.

The code may also be stored in a storage device that can direct acomputer, other programmable data processing apparatus, or other devicesto function in a particular manner, such that the instructions stored inthe storage device produce an article of manufacture includinginstructions which implement the function/act specified in the schematicflowchart diagrams and/or schematic block diagrams block or blocks.

The code may also be loaded onto a computer, other programmable dataprocessing apparatus, or other devices to cause a series of operationalsteps to be performed on the computer, other programmable apparatus orother devices to produce a computer implemented process such that thecode which execute on the computer or other programmable apparatusprovide processes for implementing the functions/acts specified in theflowchart and/or block diagram block or blocks.

The schematic flowchart diagrams and/or schematic block diagrams in theFigures illustrate the architecture, functionality, and operation ofpossible implementations of apparatuses, systems, methods and programproducts according to various embodiments. In this regard, each block inthe schematic flowchart diagrams and/or schematic block diagrams mayrepresent a module, segment, or portion of code, which includes one ormore executable instructions of the code for implementing the specifiedlogical function(s).

It should also be noted that, in some alternative implementations, thefunctions noted in the block may occur out of the order noted in theFigures. For example, two blocks shown in succession may, in fact, beexecuted substantially concurrently, or the blocks may sometimes beexecuted in the reverse order, depending upon the functionalityinvolved. Other steps and methods may be conceived that are equivalentin function, logic, or effect to one or more blocks, or portionsthereof, of the illustrated Figures.

Although various arrow types and line types may be employed in theflowchart and/or block diagrams, they are understood not to limit thescope of the corresponding embodiments. Indeed, some arrows or otherconnectors may be used to indicate only the logical flow of the depictedembodiment. For instance, an arrow may indicate a waiting or monitoringperiod of unspecified duration between enumerated steps of the depictedembodiment. It will also be noted that each block of the block diagramsand/or flowchart diagrams, and combinations of blocks in the blockdiagrams and/or flowchart diagrams, can be implemented by specialpurpose hardware-based systems that perform the specified functions oracts, or combinations of special purpose hardware and code.

The description of elements in each figure may refer to elements ofproceeding figures. Like numbers refer to like elements in all figures,including alternate embodiments of like elements.

FIG. 1 depicts an embodiment of a wireless communication system 100 fordetermining an association between DMRS and PTRS. In one embodiment, thewireless communication system 100 includes remote units 102 and baseunits 104. Even though a specific number of remote units 102 and baseunits 104 are depicted in FIG. 1 , one of skill in the art willrecognize that any number of remote units 102 and base units 104 may beincluded in the wireless communication system 100.

In one embodiment, the remote units 102 may include computing devices,such as desktop computers, laptop computers, personal digital assistants(“PDAs”), tablet computers, smart phones, smart televisions (e.g.,televisions connected to the Internet), set-top boxes, game consoles,security systems (including security cameras), vehicle on-boardcomputers, network devices (e.g., routers, switches, modems), aerialvehicles, drones, or the like. In some embodiments, the remote units 102include wearable devices, such as smart watches, fitness bands, opticalhead-mounted displays, or the like. Moreover, the remote units 102 maybe referred to as subscriber units, mobiles, mobile stations, users,terminals, mobile terminals, fixed terminals, subscriber stations, UE,user terminals, a device, or by other terminology used in the art. Theremote units 102 may communicate directly with one or more of the baseunits 104 via UL communication signals.

The base units 104 may be distributed over a geographic region. Incertain embodiments, a base unit 104 may also be referred to as anaccess point, an access terminal, a base, a base station, a Node-B, aneNB, a gNB, a Home Node-B, a relay node, a device, a core network, anaerial server, or by any other terminology used in the art. The baseunits 104 are generally part of a radio access network that includes oneor more controllers communicably coupled to one or more correspondingbase units 104. The radio access network is generally communicablycoupled to one or more core networks, which may be coupled to othernetworks, like the Internet and public switched telephone networks,among other networks. These and other elements of radio access and corenetworks are not illustrated but are well known generally by thosehaving ordinary skill in the art.

In one implementation, the wireless communication system 100 iscompliant with the 3GPP protocol, wherein the base unit 104 transmitsusing an OFDM modulation scheme on the DL and the remote units 102transmit on the UL using a SC-FDMA scheme or an OFDM scheme. Moregenerally, however, the wireless communication system 100 may implementsome other open or proprietary communication protocol, for example,WiMAX, among other protocols. The present disclosure is not intended tobe limited to the implementation of any particular wirelesscommunication system architecture or protocol.

The base units 104 may serve a number of remote units 102 within aserving area, for example, a cell or a cell sector via a wirelesscommunication link. The base units 104 transmit DL communication signalsto serve the remote units 102 in the time, frequency, and/or spatialdomain.

In one embodiment, a base unit 104 may receive information from a remoteunit 102 on an uplink channel. In certain embodiments, the base unit 104may determine a SINR for a scheduling layer for the remote unit 102based on receiving the information from the remote unit 102 on theuplink channel. Accordingly, a base unit 104 may be used for determininga SINR.

In one embodiment, a remote unit 102 may determine a configuration ofdownlink reference signal ports. In various embodiments, the remote unit102 may measure a SINR of each layer of multiple layers based on theconfiguration. Accordingly, a remote unit 102 may be used for measuringSINR.

In certain embodiments, a remote unit 102 may determine a scheduled PRBposition and bandwidth. In certain embodiments, the remote unit 102 maydetermine, based on the scheduled PRB position and bandwidth, anassociated DMRS port index within the PRB for a PTRS. Accordingly, aremote unit 102 may be used for determining an association between DMRSand PTRS.

FIG. 2 depicts one embodiment of an apparatus 200 that may be used fordetermining an association between DMRS and PTRS. The apparatus 200includes one embodiment of the remote unit 102. Furthermore, the remoteunit 102 may include a processor 202, a memory 204, an input device 206,a display 208, a transmitter 210, and a receiver 212. In someembodiments, the input device 206 and the display 208 are combined intoa single device, such as a touchscreen. In certain embodiments, theremote unit 102 may not include any input device 206 and/or display 208.In various embodiments, the remote unit 102 may include one or more ofthe processor 202, the memory 204, the transmitter 210, and the receiver212, and may not include the input device 206 and/or the display 208.

The processor 202, in one embodiment, may include any known controllercapable of executing computer-readable instructions and/or capable ofperforming logical operations. For example, the processor 202 may be amicrocontroller, a microprocessor, a central processing unit (“CPU”), agraphics processing unit (“GPU”), an auxiliary processing unit, a fieldprogrammable gate array (“FPGA”), or similar programmable controller. Insome embodiments, the processor 202 executes instructions stored in thememory 204 to perform the methods and routines described herein. Incertain embodiments, the processor 202 may determine a configuration ofdownlink reference signal ports. In various embodiments, the processor202 may measure a SINR of each layer of multiple layers based on theconfiguration. In one embodiment, the processor 202 may determine ascheduled PRB position and bandwidth. In certain embodiments, theprocessor 202 may determine, based on the scheduled PRB position andbandwidth, an associated DMRS port index within the PRB for a PTRS. Theprocessor 202 is communicatively coupled to the memory 204, the inputdevice 206, the display 208, the transmitter 210, and the receiver 212.

The memory 204, in one embodiment, is a computer readable storagemedium. In some embodiments, the memory 204 includes volatile computerstorage media. For example, the memory 204 may include a RAM, includingdynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or staticRAM (“SRAM”). In some embodiments, the memory 204 includes non-volatilecomputer storage media. For example, the memory 204 may include a harddisk drive, a flash memory, or any other suitable non-volatile computerstorage device. In some embodiments, the memory 204 includes bothvolatile and non-volatile computer storage media. In some embodiments,the memory 204 also stores program code and related data, such as anoperating system or other controller algorithms operating on the remoteunit 102.

The input device 206, in one embodiment, may include any known computerinput device including a touch panel, a button, a keyboard, a stylus, amicrophone, or the like. In some embodiments, the input device 206 maybe integrated with the display 208, for example, as a touchscreen orsimilar touch-sensitive display. In some embodiments, the input device206 includes a touchscreen such that text may be input using a virtualkeyboard displayed on the touchscreen and/or by handwriting on thetouchscreen. In some embodiments, the input device 206 includes two ormore different devices, such as a keyboard and a touch panel.

The display 208, in one embodiment, may include any known electronicallycontrollable display or display device. The display 208 may be designedto output visual, audible, and/or haptic signals. In some embodiments,the display 208 includes an electronic display capable of outputtingvisual data to a user. For example, the display 208 may include, but isnot limited to, an LCD display, an LED display, an OLED display, aprojector, or similar display device capable of outputting images, text,or the like to a user. As another, non-limiting, example, the display208 may include a wearable display such as a smart watch, smart glasses,a heads-up display, or the like. Further, the display 208 may be acomponent of a smart phone, a personal digital assistant, a television,a table computer, a notebook (laptop) computer, a personal computer, avehicle dashboard, or the like.

In certain embodiments, the display 208 includes one or more speakersfor producing sound. For example, the display 208 may produce an audiblealert or notification (e.g., a beep or chime). In some embodiments, thedisplay 208 includes one or more haptic devices for producingvibrations, motion, or other haptic feedback. In some embodiments, allor portions of the display 208 may be integrated with the input device206. For example, the input device 206 and display 208 may form atouchscreen or similar touch-sensitive display. In other embodiments,the display 208 may be located near the input device 206.

The transmitter 210 is used to provide UL communication signals to thebase unit 104 and the receiver 212 is used to receive DL communicationsignals from the base unit 104. Although only one transmitter 210 andone receiver 212 are illustrated, the remote unit 102 may have anysuitable number of transmitters 210 and receivers 212. The transmitter210 and the receiver 212 may be any suitable type of transmitters andreceivers. In one embodiment, the transmitter 210 and the receiver 212may be part of a transceiver.

FIG. 3 depicts one embodiment of an apparatus 300 that may be used fordetermining an association between DMRS and PTRS. The apparatus 300includes one embodiment of the base unit 104. Furthermore, the base unit104 may include a processor 302, a memory 304, an input device 306, adisplay 308, a transmitter 310, and a receiver 312. As may beappreciated, the processor 302, the memory 304, the input device 306,the display 308, the transmitter 310, and the receiver 312 may besubstantially similar to the processor 202, the memory 204, the inputdevice 206, the display 208, the transmitter 210, and the receiver 212of the remote unit 102, respectively.

In some embodiments, the receiver 312 may receive information from aremote unit 102 on an uplink channel. In certain embodiments, theprocessor 302 may determine a SINR for a scheduling layer for the remoteunit 102 based on receiving the information from the remote unit 102 onthe uplink channel. Although only one transmitter 310 and one receiver312 are illustrated, the base unit 104 may have any suitable number oftransmitters 310 and receivers 312. The transmitter 310 and the receiver312 may be any suitable type of transmitters and receivers. In oneembodiment, the transmitter 310 and the receiver 312 may be part of atransceiver.

FIG. 4 is a schematic block diagram illustrating one embodiment of aDMRS pattern. Specifically, the DMRS pattern is illustrated in a set ofresource elements 400. Each resource element occupies a symbol 402 in atime domain and a subcarrier 404 in a frequency domain. 14 symbols 402,and 12 subcarriers 404 are illustrated in the set of resource elements400.

In certain embodiments, DMRS may be used for channel estimation. In oneembodiment, up to 8 ports may be supported for a single UE, and up to 12ports may be supported for multiples UEs. In various embodiments, thedifferent antenna ports may be multiplexed by TDM, FDM, CDM, and/orTD/FD-OCC/TDM. As illustrated in FIG. 4 , one embodiment supports 8ports (e.g., labeled as 0, 1, 2, 3, 4, 5, 6, and 7), and FDM, TDM, andFD-OCC are used to multiplex the different DMRS antenna ports.

In some embodiments, for multi-layer single user data transmission, alllayers may be carried in the same time/frequency resources. In suchembodiments, different layers may be multiplexed by using differentprecoding vectors in a spatial domain. In certain embodiments, adecoding procedure at a receiver side may include the following threesteps.

In a first step, the receiver may derive a channel response for eachantenna port based on antenna port specific orthogonal resources. Forexample, to derive antenna port 0's channel response h, a receivedsignal r at all the REs in FIG. 4 labeled with “0/1” are received andcombined together.

In a second step, channel estimation is performed based on the receiversignal r and/or a transmitted signal s. Various algorithms may be usedto perform channel estimation (e.g., zero forcing (“ZF”), minimum meansquare error (“MMSE”), etc.). After channel estimation, an estimatedchannel for each antenna port may be derived. For example, antenna port0's channel response is estimated as h′.

In a third step, estimated channel response is used to recover data. Fora 4 layer SU-MIMO transmission, channel response at antenna ports 0, 1,2, and 3 may be derived individually and used to construct a receiverside processing matrix. Based on the received data signal (r1, r2, . . ., r_RX) at different receive antenna elements, the data may berecovered, and input to further processing units.

In some embodiments, for multi-layer multiple user data transmissions,the above three steps may be used with a few changes. The maindifference is that the total number of ports are divided by differentUEs. For example, antenna ports 0, 1, 2, and 3 are used for a first UEand antenna ports 4, 5, 6, and 7 are used for a second UE. The first andsecond UEs data share the same time/frequency resources. Precodingvectors corresponding to antenna ports 0, 1, 2, and 3 are used for thefirst UE's data transmission, and precoding vectors corresponding toantenna ports 4, 5, 6, and 7 are used for the second UE's datatransmission. From a signaling perspective, a UE may need to know thedetailed antenna ports for its own usage. That is, antenna ports 0, 1,2, and 3 need to be indicated to the first UE, and antenna ports 4, 5,6, and 7 need to be indicated to the second UE.

FIG. 5 is a schematic block diagram illustrating one embodiment of aPTRS pattern. Specifically, the PTRS pattern is illustrated in a set ofresource elements 500. Each resource element occupies a symbol 502 in atime domain and a subcarrier 504 in a frequency domain. 14 symbols 502,and 12 subcarriers 504 are illustrated in the set of resource elements500.

In certain embodiments, PTRS may be used to track a phase difference ina time domain. In various embodiments, PTRS may mainly be used for highspeed and larger subcarriers. One embodiment of a PTRS pattern isillustrated in FIG. 5 .

In certain embodiments, a time domain PTRS density is related to ascheduled MCS. Accordingly, with the scheduled MCS value and RRCconfigured MCS and/or density mapping, PTRS bearing symbols in the timedomain may be derived.

In various embodiments, a frequency domain PTRS density may be relatedto a scheduled bandwidth. With the scheduled bandwidth and RRCconfigured bandwidth and/or density mapping, the PTRS bearing PRB in thefrequency domain can be derived. In some embodiments, the PTRS REposition within a PTRS bearing PRB may be determined using severalfactors. For example, the PTRS RE position may be near an associatedDMRS port RE position to provide accurate phase tracking performance. Incertain embodiments, PTRS may be shifted or punctured to avoid collisionwith other reference signals, such as CSI-RS, SS block, and/or PDCCHtime and/or frequency resources.

In one embodiment, a PTRS port number is related to a transmitter sideTRP and/or panel number due to separate oscillators. In certain MU-MIMOconfigurations, different users may use separate PTRS due to differentprecoding vectors. In such embodiments, multiplexing may be completedusing FDM, TDM, or CDM.

In various embodiments, a DMRS is used to estimate a channel from one ortwo DMRS bearing symbols, and interpolation may be used to get a channelresponse in other non-DMRS symbols. In some embodiments, such as withhigh frequency band and high speed, a channel may change moredynamically in the frequency domain. As such, PTRS may be used toestimate the phase difference, and combined with channel estimationbased on DMRS, to get a channel response for all the symbols.

In certain embodiments, for a single UE, multiple DMRS ports form a DMRSport group to perform SU MIMO transmission. The DMRS port group maycorrespond to a TRP or panel. In various embodiments, a single PTRS portmay be used for a single UE, and the PTRS port may be associated with aTRP or panel. As a result, there may be a PTRS port associated with aDMRS port group, and the PTRS port may share the same precoding vectorwith one of the DMRS ports.

In a first embodiment for PTRS and DMRS port association, if one DL PTRSport is configured for a DL DMRS port group, the DL PTRS port and one DLDMRS port in the DL DMRS port group are associated for phase tracking,the association may be determined in a specification.

In a second embodiment for PTRS and DMRS port association, if one DLPTRS port is configured for a DL DMRS port group, the DL PTRS port isassociated with one of the following: a first option in which the lowestDL DMRS port in the DL DMRS port group; or a second option in which oneDL DMRS port in the DL DMRS port group in a RB, where the one DL DMRSport may vary across RBs.

In some embodiments, with the first option, a DMRS port 0 may be chosento be associated with the PTRS port, that is, the PTRS port may sharethe same precoding vector with DMRS port 0. In various embodiments,because the SINR on different DMRS ports may be different, and thelargest SINR port may change for different channel characteristics, thePTRS port may be associated with the DMRS port having the largest SINR.

In certain embodiments, to obtain the largest SINR for DMRS port 0, aprecoder permutation may be used. For example, with precoderpermutation, DMRS port 0 may always be associated the largest SINR ofthe channel. Meanwhile, in some embodiments, data layer 0 may alsoalways be associated with the largest SINR of the channel. In suchembodiments, this may lead to SINR imbalance among different layersand/or CWs.

In various embodiments, with the second option, an association betweenPTRS and DMRS may change from PRB to PRB. In such embodiments, this mayprovide some kind of frequency domain diversity; however, it may impactthe coexistence of PTRS and other reference signals.

FIG. 6 is a schematic flow chart diagram illustrating one embodiment ofa method 600 for swapping MCS and/or TBS between two CWs.

In certain embodiments, the method 600 includes reporting 602 CQIACK/NACK for two CWs (e.g., as in a regular case or in response tochannel measurement based on uplink signals and/or channels in a channelreciprocity case). In some embodiments, two CWs may be used in responseto the rank indication being larger than 4, otherwise, one CW may beused.

In various embodiments, the method 600 includes performing 604 CW tolayer mapping and determining a NDI based on a first transmission or aretransmission. In certain embodiments, in response to completing CW tolayer mapping, the method 600 determines 606 whether there is a precoderpermutation across different codewords. When there are multiple layersfor transmission, the precoding matrix contains multiple columns, andeach column corresponds to a transmission layer and corresponds to aprecoding vector. As used herein, precoder permutation means one or moreprecoding vectors are exchanged (e.g., swapped) among differenttransmission layers. When the exchanged transmission layers belong todifferent CWs, there is precoder permutation among different codewords.

In response to the method 600 determining 606 that there are differentprecoder permutation across different CWs, the method 600 may swap 608MCS and/or TBS between the two CWs and keep the NDI the same in the CWs(e.g., not swap the NDI). In another embodiment, the MCS for the two CWscan also be recalculated based on the permutated precoding matrix. Inone embodiment, the precoder permutation may be a one-to-onepermutation; while, in another embodiment, the precoder permutation maybe a group-to-group permutation. For example, if there are 5 layers intotal for data transmission, layers 0 and 1 may be used for a firstcodeword (“CW0”), and layers 2, 3, and 4 may be used for a secondcodeword (“CW1”). If layer 2 is the highest SINR layer (e.g., layer 2has the highest SINR out of all the layers), the precoding vector oflayer 0 and layer 2 may be exchanged. In addition, in certainembodiments, the precoding vector of layer 1 and layer 3 may also beexchanged.

Turning to FIG. 7 , FIG. 7 is a schematic block diagram illustrating oneembodiment of MCS and TBS in two CWs 700 before swapping the MCS andTBS. CW0 702 is associated with MCS0/TBS0/NDI0 based on base unit 104scheduling, and CW1 704 is associated with MCS1/TBS1/NDI1 based on baseunit 104 scheduling.

Turning to FIG. 8 , FIG. 8 is a schematic block diagram illustrating oneembodiment of MCS and TBS in two CWs 800 after swapping the MCS and TBS.If data layer 0 and data layer 3 are swapped so that the largest SINR istransmitted on data layer 0, then new CW0 802 will be associated withMCS1/TBS1/NDI0, and new CW1 804 will be associated with MCS0/TBS0/NDI1.As data layer 0 share the same precoding vector as DMRS port 0, and datalayer 3 share the same precoding vector as DMRS port 3, the precodingvectors for DMRS port 0 and 3 are also swapped. In some embodiments,MCS0, TBS0, MCS1, and/or TBS1 may be recalculated based on the new layergrouping. In certain embodiments, a base unit 104 may derive thedetailed SINR of each layer based on an uplink channel measurement in achannel reciprocity case or per layer SINR feedback (or other feedbacksuch as CQI) from a UE. In various embodiments, if there is only CQIreporting for the two CWs as in regular case, the two CQI values may becompared. In such an embodiment, if the CQI of CW1 is better than thatof CW0, precoder column permutation may be performed between layer 0 andthe smallest layer of CW1. In some embodiments, if there is precoderpermutation within a single CW, MCS/TBS selection may be performed as inregular case.

Returning to FIG. 6 , in response to the method 600 determining 606 thatthere are not different precoder permutation across different CWs, themethod 600 may map 610 MCS and/or TBS without swapping (e.g., ACK/NACKfeedback for the two CWs may be performed as in a regular case). Incertain embodiments, the CWs may be retransmission with NACK feedback,and may indicate a corresponding retransmission via NDI for each CW. Insome embodiments, the method 600 may use no additional signalingoverhead and be transparent to a UE; however, there may be a mismatchbetween the swapped MCS/TBS and channel characteristics.

Turning to FIG. 9 , FIG. 9 is a schematic flow chart diagramillustrating one embodiment of a method 900 for precoder permutation.The method 900 may include a UE measuring 902 a channel response basedon a configured CSI-RS. The method 900 may also include the UEdetermining 904 a reporting rank based on the measured channel response.The method 900 may include the UE calculating 906 a SINR value for eachlayer. In certain embodiments, instead of calculating 906 the SINR, theUE may calculate another value, such as CQI, a singular value, and soforth.

The method 900 determines 908 whether the rank is larger than 4. Inresponse to the method 900 determining 908 that the rank is larger than4, the method 900 may map 910 first floor (e.g., (number of layers/2)rounded down) layers to CW0 and remaining layers to CW1. For example,when the rank is 5, then layers 0 and 1 may be mapped to CW0 and layers2, 3, and 4 may be mapped to CW1. In some embodiments, the method 900may map layers in other ways. In response to the method 900 determining908 that the rank is less than or equal to 4, the method 900 may map 912all layers to CW0. For example, when the rank is 4, then layers 0, 1, 2,and 3 may be mapped to CW0.

The method 900 may determine 914 whether the largest SINR layer is layer0. In response to the method 900 determining 914 that the largest SINRlayer is not layer 0, then the method 900 may perform 916 layerpermutation between layer 0 and the largest SINR layer. In certainembodiments, the layer permutation may be performed between layer groupsof CW0 and CW1, especially if a number of layers of two CWs are thesame. The method 900 may calculate 918 the CQI based on the permutatedlayers for the one or two CWs. In some embodiments, the method 900 maydetermine the CQI for the one or two CWs based on the layer mappingbefore permutation if the layers of two CWs are the same. In variousembodiments, the method 900 may report 920 CQI, RI, PMI, and/orpermutation information. In certain embodiments, the UE may report thelargest SINR layer before permutation for permutation reporting. Forexample, if the maximum transmission layer is 8, then 3 bits may be usedto indicate which layer is permutated. If 100 is indicated, it may meanthat layer 4 is changed with layer 0. The reported CQI may be the CQIdetermined from the calculation 918, and the RI may be the rank fromdetermining 904. In some embodiments, PMI before permutation may bereported so that codebook design may not be impacted.

In some embodiments, the base unit 104 may reconstruct the precodingvector based on the reported PMI and the permutation reporting. Forexample, if 010 is reported in the permutation reporting, then column 0and column 4 in the reported precoding matrix may be exchanged. If thepermutation is per group, and 100 is reported in the permutationreporting, it may mean that layer 4 is the largest SINR layer, and iflayer 4 belongs to CW1, then columns 0, 1, 2, and 3 and columns 4, 5, 6,and 7 in the reported precoding matrix may be exchanged respectively.

In certain embodiments, the base unit 104 performs updates to theconstructed precoding vector and the reported CQI and/or RI ifnecessary. In some embodiments, the method 900 may have a reported CQIvalue that matches with the permutated precoding vector; however, themethod 900 may increase UE complexity and overhead compared to method600.

In some embodiments, for a MU case, each UE may have its own UE specificPTRS port. In such embodiments, precoder column permutation may beperformed per user. In various embodiments, if the CW for each MU UE isrestricted to 1, precoder column permutation may be performed at thetransmitter side for each UE, and due to the same MCS/TBS/CQI fordifferent layers of the single CW for each UE, there may be noperformance impact. For example, if ports 0 and 1 are used for UE1, andports 2 and 3 are used for UE2. For UE1, if port 1 has a larger SINRthan port 0, then permutation between port 0 and port 1 may be performedat the transmitter side. For UE2, if port 3 has the largest SINR, thenpermutation between port 2 and port 3 may also be performed attransmitter side. If two codewords are used for each MU UE, bothtransmitter side permutation and UE side permutation may be used.

In certain embodiments, transmitter side permutation for scheduled MUUEs may be used. For example, ports 0 and 1, and CW0 and CW1 may be usedfor UE1, and ports 2 and 3 and CW0 and CW1 may be used for UE2. UE1 andUE2 may be scheduled in the same time and/or frequency resources. Insuch embodiments, transmission power of both UE1 and UE2 may be reducedby 3 dB due to the same time/frequency resources being used. In certainembodiments, UE1 has its own UE specific PTRS port 0 for phase tracking,and UE2 also has its own UE specific PTRS port 0 for phase tracking. ForUE1, if port 0 SINR is smaller than that of port 1, precoder columnpermutation for layer 0 and layer 1 may be performed. Moreover, MCS/TBSswapping may be performed for UE1's two CWs. Similar operation may beused by UE2. In various embodiments, UE side permutation for eachscheduled MU UE may be used.

In certain embodiments, the frequency domain PTRS density may be relatedto the scheduled bandwidth. That is, based on an RRC configuredbandwidth-density mapping table, with the scheduled bandwidth in DCIformat, a UE may derive the PTRS bearing PRB. For example, if thescheduled bandwidth is 30 PRB, and the corresponding density is ⅓ by themapping table, then the UE can derive that PRBs 0, 3, 6, 9, 12, 15, 18,21, 24, and 27 are the PTRS bearing PRBs. For a single PTRS port, asingle RE in a PRB may be used. In such embodiments, the detailed PTRSRE position may be related to the associated DMRS port.

In various embodiments, a UE may be allocated to multiple DMRS ports forspatial multiplexing operations. Different DMRS ports may be multiplexedby FDM, TDM, and/or CDM to provide accurate channel estimation. Forexample, DMRS port 0 may be associated with REs including 0/1 and 4/5 inFIG. 4 , and DMRS port 2 may be associated with REs including 2/3 and6/7 in FIG. 4 . If PTRS port 0 is associated with DMRS port 0, then thePTRS RE position should be limited with REs including 0/1 and 4/5 due tosimilar channel characteristics for neighboring REs, and the precodingvector should be the same for PTRS port 0 and DMRS port 0. If PTRS port0 is associated with DMRS port 2, then the PTRS RE position should belimited to REs including 2/3 and 6/7, and PTRS port 0 share the sameprecoding vector with DMRS port 2.

In various embodiments, the associated DMRS port for PTRS may changefrom PRB to PRB. This may mean that the precoding vector and the REposition of a PTRS port may be changed from PRB to PRB. With such anembodiment, frequency domain diversity may be achieved as this issimilar to precoder cycling in the frequency domain.

In certain embodiments, the RE position within a PRB is changed from PRBto PRB. This may mean that the PTRS port 0 frequency domain distributionis not even. Moreover, there may some performance impact due to unevendistribution if interpolation is used in frequency domain. In someembodiments, coexistence between PTRS and other RS and/or channels maybe common. The possible coexisted RS and/or channels may be CSI-RS, SSblock, PDCCH control resources, and/or data. If PTRS always has thelowest priority, then may be no impact to other RS and/or channels.However, other RS and/or channels may use puncturing, shifting, and/ordropping to avoid PTRS time/frequency resources. In various embodiments,there may be different puncturing, shifting, and/or dropping patterns indifferent PTRS bearing PRBs.

In some embodiments, the RE position for a PTRS bearing PRB may be knownto the UE. In certain embodiments, there may be an implicit way toderive the associated DMRS port for each PTRS bearing PRB. For example,a UE may derive the associated DMRS port for each PTRS bearing PRB basedon a scheduled PRB position and bandwidth. In various embodiments, thePTRS bearing PRB with a smallest PRB index is associated with DMRS port0. In various embodiments, with an increasing PRB index, the associatedDMRS port index may also increase ((e.g., 0, 1, . . . max DMRS portindex, 0, 1, . . . ) mapped to each PTRS bearing PRB respectively). Insome embodiments, a max DMRS port may be indicated in DCI. As anotherexample, deriving the associated DMRS port for each PTRS bearing PRB maybe cell specific and may be derived by extending the PTRS bearing PRB tothe total system bandwidth (e.g., by mapping the DMRS port index (0, 1,. . . , max DMRS port index, 0, 1, . . . ) to the PTRS bearing PRB ofthe system bandwidth). For a single UE, the part corresponding to thescheduled bandwidth may be used. For example, the DMRS port index may be0, 1, . . . , max DMRS port index, and the PTRS bearing PRB index fromthe start of the carrier bandwidth or bandwidth part may be indexed as0, 1, 2, . . . , max PTRS bearing PRB index. If the UE allocatedbandwidth part overlaps with PTRS bearing PRB i, i+1, . . . , j, thenthe associated DMRS port are i mod (max_DMRS_port_index+1), (i mod(max_DMRS_port_index+1))+1, . . . , respectively. In certainembodiments, a difference between UE specific and cell specific derivingof the associated DMRS port for each PTRS bearing PRB may be that astarting DMRS port index is changed and/or that cell specific may bebetter for DMRS port starting index randomization.

In some embodiments, explicit signaling may be used to indicate anassociated DMRS port index for the smallest PTRS bearing PRB index. Suchsignaling may be performed using DCI signaling and/or RRC signaling. Incertain embodiments, if the possible max DMRS ports for a single UE is8, then 3 bits may be used for signaling.

In various embodiments, a hopping pattern may be used. In suchembodiments, a hopping step may be any suitable value, such as 0, 1, 2,etc. In some embodiments, a 0 may indicate the DMRS port indexdifference between two CWs. For example, if there are two CWs, CW0 isassociated with DMRS port indexes 0, 1, and 2, and CW1 is associatedwith DMRS port indexes 3, 4, 5, and 6, then the first, third, and fifthPTRS bearing PRBs are associated with DMRS ports having indexes 0, 1,and 2, respectively, and the second, fourth, sixth, and eighth PTRSbearing PRB are associated with DMRS ports having indexes 3, 4, 5, and6, respectively. In various embodiments, the PTRS bearing PRBs arere-indexed as 0, 1, 2 . . . . In such embodiments, a hopping step of 1indicates that the difference between two adjacent DMRS port indexes isone times the difference between adjacent PTRS bearing PRBs re-indexedindices. Moreover, a hopping step of 2 indicates that the differencebetween two adjacent DMRS ports is two times the difference of adjacentPTRS bearing PRBs re-indexed indices. For example, if there are DMRSports 0, 1, 2, and 3, and PTRS bearing PRB index 00, 01, 02, 03, and 04,when the hopping step is 2, then PTRS PRB index 00 is associated withDMRS port 0, PTRS PRB index 01 is associated with DMRS port 2, PTRS PRBindex 02 is associated with DMRS port 0, PTRS PRB index 03 is associatedwith DMRS port 2, PTRS PRB index 04 is associated with DMRS port 0. Asanother example, if there are DMRS ports 0, 1, 2, and 3, and PTRSbearing PRB index 00, 01, 02, 03, and 04, when the hopping step is 1,then PTRS PRB index 00 is associated with DMRS port 0, PTRS PRB index 01is associated with DMRS port 1, PTRS PRB index 02 is associated withDMRS port 2, PTRS PRB index 03 is associated with DMRS port 3, PTRS PRBindex 04 is associated with DMRS port 0.

In one embodiment, hopping information may be signaled explicitly usingDCI signaling and/or RRC signaling. In such embodiments, the hoppinginformation may be signaled using 1 or 2 bits. In various embodiments,hopping information may be determined implicitly based on a scheduledbandwidth and a max DMRS port index. For example, if the number of PTRSbearing PRBs is larger than the max DMRS port index, hopping_step=1;otherwise,hopping_step=ceil(max_DMRS_port_index/PTRS_bearing_PRB_number) orfloor(max_DMRS_port_index/PTRS_bearing_PRB_number).

In some embodiments, a default hopping step may be used. For example, ifthere are two codewords, a hopping step may equal 0 as a defaultbehavior, and if there is only one codeword, a hopping step may equal 1as the default behavior. In certain embodiments, if the associated DMRSport in a PTRS bearing PRB is known, then the RE position may bedetermined.

In certain embodiments, the PTRS for a UE may be associated with theDMRS port having the largest SINR in each PTRS bearing PRB. In suchembodiments, there may be multiple ways to derive the associated DMRSport in each PTRS bearing PRB. One way to derive the associated DMRSport in each PTRS bearing PRB may be based on UE blind detection. Usingblind detection, the UE may perform channel estimation on all assignedDMRS ports in a scheduled subframe for each PTRS bearing PRB, and basedon the channel estimation result, the largest SINR DMRS port for a PTRSbearing PRB may be derived. Another way to derive the associated DMRSport in each PTRS bearing PRB may be based on a base unit 104 indicationof associated DMRS port for each PTRS bearing PRB; however, there may belarge overhead for this.

In some embodiments, coexistence of other RS and/or channels may beknown to the base unit 104 before scheduling, so puncturing, shifting,and/or dropping of corresponding RS and/or channels may be done by thebase unit 104. In certain embodiments, a UE may derive puncturing,shifting, and/or dropping behavior after decoding DCI signaling based onpredefined rules, and then it may avoid misdetection.

In various embodiments, each UE may have a UE specific PTRS. Moreover,MU UEs may have different transmission layers. In some embodiments, MUmay be transparent to a UE from DMRS perspective. In this case, the DMRSports of a single UE and multiple UEs may occupy the same time/frequencyresource, and the DMRS ports may code division multiplexed. In certainembodiments, the PTRS RE position may be restricted to be associatedwith the smallest DMRS port index per UE. In some embodiments, theprecoding vector may be different for different PTRS bearing PRBs. Anexample is illustrated in FIGS. 10 and 11 .

FIG. 10 is a schematic block diagram illustrating one embodiment of DMRSfor multiple users. Specifically, a DMRS pattern is illustrated in a setof resource elements 1000. Each resource element occupies a symbol 1002in a time domain and a subcarrier 1004 in a frequency domain. 14 symbols1002, and 12 subcarriers 1004 are illustrated in the set of resourceelements 1000. UE1 is assigned DMRS port 0, UE2 is assigned DMRS port 2,and UE3 (e.g., a third UE) is assigned DMRS ports 2 and 3. The DMRS ofthese UEs occupy the same time/frequency resources as shown in FIG. 10 .

FIG. 11 is a schematic block diagram illustrating one embodiment of PTRSfor multiple users. Specifically, a PTRS pattern is illustrated in a setof resource elements 1100. Each resource element occupies a symbol 1102in a time domain and a subcarrier 1104 in a frequency domain. 14 symbols1102, and 12 subcarriers 1104 are illustrated in the set of resourceelements 1100. In some embodiments, each UE has its own UE specificPTRS. The PTRS share the same RE position, which is RE position 0. Theprecoding vector of UE specific PTRS may be related to the associatedDMRS port. UE1's PTRS port 0 may share the same precoding vector as DMRSport 0, UE2's PTRS port 0 may share the same precoding vector as DMRSport 1, and UE's PTRS port 0 may share the same precoding vector of DMRSport 2 or 3, depending on the PTRS bearing PRB index as in SU case.

In certain embodiments, MU may be non-transparent to UE from DMRSperspective. In this case, both DMRS and PTRS occupation need to beinformed to the co-scheduling UE for rate matching. In some embodiments,the PTRS RE position frequency hopping pattern may be known to theco-scheduled UE. In this case, the cell specific PTRS RE positionhopping pattern based on the system bandwidth may be used, due to thefact that MU UEs may only have partial overlap bandwidth. In variousembodiments, there may be a default pattern hopping step or the hoppingstep may be explicitly signaled by RRC signaling and/or DCI signaling.

In various embodiments, DFTS-OFDM may be used. In such embodiments,there may be pre-DFT insertion of PTRS. Moreover, if the associated DMRSport changes, multiplexing of data and PTRS may change from PRB to PRB.For example, in PTRS bearing PRB 0, PTRS port 0 may be associated withDMRS port 0, and multiplexed with data layer 0, and in PTRS bearing PRB1, PTRS port 0 may be associated with DMRS port 1, and multiplexed withdata layer 1. In certain embodiments, if always associated with DMRSport 0, PTRS may always be multiplexed with data layer 0. In someembodiments, precoder column permutation may be used to result in thelargest SINR for DMRS port 0. MCS and/or CQI swapping at the transmitterside and UE side operation may also be used. As may be appreciated, thevarious embodiments described herein may be used for DL and/or UL.

FIG. 12 is a schematic flow chart diagram illustrating one embodiment ofa method 1200 for determining a SINR. In some embodiments, the method1200 is performed by an apparatus, such as the base unit 104. In certainembodiments, the method 1200 may be performed by a processor executingprogram code, for example, a microcontroller, a microprocessor, a CPU, aGPU, an auxiliary processing unit, a FPGA, or the like.

The method 1200 may include receiving 1202 information from a remoteunit 102 on an uplink channel. In certain embodiments, the method 1200includes determining 1204 a signal-to-interference-plus-noise ratio fora scheduling layer for the remote unit 102 based on receiving theinformation from the remote unit on the uplink channel.

In one embodiment, the information from the remote unit on the uplinkchannel includes a report from the remote unit. In certain embodiments,the report includes channel quality indication reporting correspondingto two code words. In various embodiments, in response to a channelquality indication of a second codeword of the two code words indicatinga better channel quality than a channel quality indication of a firstcodeword of the two codewords, the method 1200 includes swapping amodulation and coding scheme, a transport block size, or a combinationthereof of the first and second codewords in downlink controlinformation.

In some embodiments, in response to a channel quality indication of asecond codeword of the two code words indicating a better channelquality than a channel quality indication of a first codeword of the twocodewords, the method 1200 includes performing a precoder columnpermutation for layer 0 and a smallest layer of the second codeword. Inone embodiment, the report includes signal-to-interference-plus-noiseratio reporting or channel quality indication reporting for each layerof multiple layers. In a further embodiment, in response to asignal-to-interference-plus-noise ratio report of layer 0 not being abest signal-to-interference-plus-noise ratio report or a channel qualityindication report of layer 0 not being a best channel quality indicationreport, the method 1200 includes performing a precoder columnpermutation for layer 0 and a layer having the bestsignal-to-interference-plus-noise ratio report or the best channelquality indication report.

In certain embodiments, in response to the layer having the bestsignal-to-interference-plus-noise ratio report or the best channelquality indication report belonging to a second codeword, the method1200 includes swapping a modulation and coding scheme, a transport blocksize, or a combination thereof of the first codeword and a secondcodewords in downlink control information. In various embodiments, thesignal-to-interference-plus-noise ratio is based on a measurement of theuplink channel. In one embodiment, in response to asignal-to-interference-plus-noise ratio of layer 0 not being a largestsignal-to-interference-plus-noise ratio based on the measurement, themethod 1200 includes performing a precoder column permutation for layer0 and a layer having the largest signal-to-interference-plus-noiseratio. In some embodiments, in response a largestsignal-to-interference-plus-noise ratio based on the measurementbelonging to a second codeword, the method 1200 includes performing aprecoder column permutation between the first codeword and a secondcodeword.

In various embodiments, in response a largestsignal-to-interference-plus-noise ratio based on the measurementbelonging to a second codeword, the method 1200 includes swapping amodulation and coding scheme, a transport block size, or a combinationthereof of the first codeword and a second codewords in downlink controlinformation. In certain embodiments, in response a largestsignal-to-interference-plus-noise ratio based on the measurementbelonging to a second codeword, the method 1200 includes recalculating amodulation and coding scheme, a transport block size, or a combinationthereof of the first codeword and indicating the modulation and codingscheme, the transport block size, or a combination thereof in downlinkcontrol information.

FIG. 13 is a schematic flow chart diagram illustrating one embodiment ofa method 1300 for measuring SINR. In some embodiments, the method 1300is performed by an apparatus, such as the remote unit 102. In certainembodiments, the method 1300 may be performed by a processor executingprogram code, for example, a microcontroller, a microprocessor, a CPU, aGPU, an auxiliary processing unit, a FPGA, or the like.

The method 1300 may include determining 1302 a configuration of downlinkreference signal ports. In various embodiments, the method 1300 includesmeasuring 1304 a signal-to-interference-plus-noise ratio of each layerof multiple layers based on the configuration.

In one embodiment, the method 1300 includes performing codeword to layermapping based on a number of layers of the multiple layers. In certainembodiments, the method 1300 includes transmitting a report including alargest signal-to-interference-plus-noise ratio layer based on measuringthe signal-to-interference-plus-noise ratio of each layer.

In various embodiments, the method 1300 includes determining a precodingmatrix based on measuring the signal-to-interference-plus-noise ratio ofeach layer. In some embodiments, each column of the precoding matrixincludes a precoding vector, and each precoding vector is determinedbased on a corresponding layer of the multiple layers. In oneembodiment, in response to a largest signal-to-interference-plus-noiseratio corresponding to a layer that is not layer 0, the method 1300includes exchanging in the precoding matrix the precoding vector forlayer 0 with the precoding vector for the layer having the largestsignal-to-interference-plus-noise ratio to produce a permutatedprecoding matrix. In a further embodiment, the method 1300 includesdetermining a channel quality indication for each codeword of multiplecodewords based on the permutated precoding matrix. In certainembodiments, the method 1300 includes transmitting a report includingthe channel quality indication for each codeword. In variousembodiments, a base unit determines the permutated precoding matrixbased on a layer having a largest signal-to-interference-plus-noiseratio and the precoding matrix. In one embodiment, the method 1300includes transmitting a report including the precoding matrix.

FIG. 14 is a schematic flow chart diagram illustrating one embodiment ofa method 1400 for determining an association between DMRS and PTRS. Insome embodiments, the method 1400 is performed by an apparatus, such asthe remote unit 102. In certain embodiments, the method 1400 may beperformed by a processor executing program code, for example, amicrocontroller, a microprocessor, a CPU, a GPU, an auxiliary processingunit, a FPGA, or the like.

The method 1400 may include determining 1402 a scheduled physicalresource block position and bandwidth. In certain embodiments, themethod 1400 includes determining 1404, based on the scheduled physicalresource block position and bandwidth, an associated demodulationreference signal port index within the physical resource block for aphase tracking reference signal.

In one embodiment, the method 1400 includes associating the phasetracking reference signal to a demodulation reference signal port basedon the physical resource block bearing phase tracking reference signalwith a smallest physical resource block index. In certain embodiments,the method 1400 includes associating the phase tracking reference signalto the smallest demodulation reference signal port index for thephysical resource block bearing phase tracking reference signal withsmallest physical resource block index.

In various embodiments, the method 1400 includes associating, based on ascheduled physical resource block position in a carrier or bandwidthpart, the phase tracking reference signal to a demodulation referencesignal port index for the physical resource block bearing phase trackingreference signal with smallest physical resource block index. In someembodiments, the method 1400 includes associating the phase trackingreference signal to the indicated demodulation reference signal port indownlink control information, radio resource control, or a combinationthereof for the physical resource block bearing phase tracking referencesignal with smallest physical resource block index. In one embodiment,the method 1400 includes determining a demodulation reference signalport index difference for adjacent phase tracking reference signalsbearing physical resource blocks. In a further embodiment, thedetermined demodulation reference signal port index difference is basedon a demodulation reference signal port difference between twocodewords. In certain embodiments, the determined demodulation referencesignal port index difference is based on a default value. In variousembodiments, the determined demodulation reference signal port indexdifference is based on signaling by downlink control information, radioresource control, or a combination thereof. In one embodiment, thesignaling is part of an uplink grant or a downlink assignment.

In some embodiments, the method 1400 includes determining a phasetracking reference signal resource element position within a physicalresource block based on the demodulation reference signal port index. Incertain embodiments, the method 1400 includes determining a phasetracking reference signal precoding vector to be the same as a precodingvector of the associated demodulation reference signal port. In variousembodiments, the method 1400 includes determining a phase trackingreference signal resource element position within a physical resourceblock based on a smallest demodulation reference signal port index. Insome embodiments, the method 1400 includes determining a phase trackingreference signal resource element position within a physical resourceblock based on radio resource control signaling.

Embodiments may be practiced in other specific forms. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. An apparatus for wireless communication, the apparatus comprising: aprocessor; and a memory coupled to the processor, the processorconfigured to cause the apparatus to: determine a configuration ofdownlink reference signal ports; and measure asignal-to-interference-plus-noise ratio of each layer of a plurality oflayers based on the configuration.
 2. The apparatus of claim 1, whereinthe processor is configured to cause the apparatus to perform codewordto layer mapping based on a number of layers of the plurality of layers.3. The apparatus of claim 1, wherein the processor is configured tocause the apparatus to report a largestsignal-to-interference-plus-noise ratio layer based on measuring thesignal-to-interference-plus-noise ratio of each layer.
 4. The apparatusof claim 1, wherein the processor is configured to cause the apparatusto determine a precoding matrix based on measuring thesignal-to-interference-plus-noise ratio of each layer.
 5. The apparatusof claim 4, wherein each column of the precoding matrix comprises aprecoding vector, and each precoding vector is determined based on acorresponding layer of the plurality of layers.
 6. The apparatus ofclaim 5, wherein the processor is configured to cause the apparatus to,in response to a largest signal-to-interference-plus-noise ratiocorresponding to a layer that is not layer 0, exchange in the precodingmatrix the precoding vector for layer 0 with the precoding vector forthe layer having the largest signal-to-interference-plus-noise ratio toproduce a permutated precoding matrix.
 7. The apparatus of claim 6,wherein the processor is configured to cause the apparatus to determinea channel quality indication for each codeword of a plurality ofcodewords based on the permutated precoding matrix.
 8. The apparatus ofclaim 7, wherein the processor is configured to cause the apparatus toreport the channel quality indication for each codeword.
 9. Theapparatus of claim 6, wherein a base unit determines the permutatedprecoding matrix based on a layer having a largestsignal-to-interference-plus-noise ratio and the precoding matrix. 10.The apparatus of claim 4, wherein the processor is configured to causethe apparatus to report the precoding matrix.
 11. A method for wirelesscommunication, the method comprising: determining a configuration ofdownlink reference signal ports; and measuring asignal-to-interference-plus-noise ratio of each layer of a plurality oflayers based on the configuration.
 12. The method of claim 11, furthercomprising performing codeword to layer mapping based on a number oflayers of the plurality of layers.
 13. The method of claim 11, furthercomprising reporting a largest signal-to-interference-plus-noise ratiolayer based on measuring the signal-to-interference-plus-noise ratio ofeach layer.
 14. The method of claim 11, further comprising determining aprecoding matrix based on measuring thesignal-to-interference-plus-noise ratio of each layer.
 15. The method ofclaim 14, wherein each column of the precoding matrix comprises aprecoding vector, and each precoding vector is determined based on acorresponding layer of the plurality of layers.
 16. The method of claim15, further comprising, in response to a largestsignal-to-interference-plus-noise ratio corresponding to a layer that isnot layer 0, exchanging in the precoding matrix the precoding vector forlayer 0 with the precoding vector for the layer having the largestsignal-to-interference-plus-noise ratio to produce a permutatedprecoding matrix.
 17. The method of claim 16, further comprisingdetermining a channel quality indication for each codeword of aplurality of codewords based on the permutated precoding matrix.
 18. Themethod of claim 17, further comprising reporting the channel qualityindication for each codeword.
 19. The method of claim 16, wherein a baseunit determines the permutated precoding matrix based on a layer havinga largest signal-to-interference-plus-noise ratio and the precodingmatrix.
 20. The method of claim 14, further comprising reporting theprecoding matrix.